arduino

Due largely to the overwhelming dominance of mobile phones, payphones are a sometimes overlooked relic from the 90’s and earlier eras. While seldom seen out in the wild these days, they can however still be acquired for a moderate fee — how many of you knew that? Setting out to prove the lasting usefulness of the payphone, Instructables user [Fuzzy-Wobble] has dialed the retro spirit way past eleven to his ’90 from the ’90s’ payphone boombox.

Conspicuously mounted in the corner of his office, a rangefinder sets the phone to ringing when somebody walks by — a fantastic trap for luring the curious into a nostalgia trip. Anyone who picks up will be prompted to punch in a code from the attached mini-phone book and those who do will be treated to one of ninety hits from — well — the 1990’s. All of the songs have been specifically downgraded to 128kbps for that authentic 90’s sound — complete with audio artifacts. There’s even a little easter egg wherein hitting the coin-return lever triggers the payphone to shout “Get a job!”

Imagine trying to make a ball-shaped robot that rolls in any direction but with a head that stays on. When I saw the BB-8 droid doing just that in the first Star Wars: The Force Awakens trailer, it was an interesting engineering challenge that I couldn’t resist. All the details for how I made it would fill a book, so here are the highlights: the problems I ran into, how I solved them and what I learned.

There’s an iconic scene from the movie Big where [Tom Hanks] and [Robert Loggia] play an enormous piano by dancing around on the floor-mounted keys. That was the first thing we thought of when we saw [jegatheesan.soundarapandian’s] PC joystick rug. His drum playing (see the video below) wasn’t as melodious as [Hanks] and [Loggia] but then again they probably had a musical director.

At the heart of the project is, of course, an Arduino. An HC-05 provides a Bluetooth connection back to the PC. We thought perhaps an Arduino with USB input capability like the Leonardo might be in use, but instead, [jegatheesan] has a custom Visual Basic program on the PC that uses SendKeys to do the dirty work.

The switches are more interesting made with old CDs, foil, and sponges. The sponge holds the CDs apart until you step on them and the foil makes the CDs conductive. He uses a lot of Fevicol in the project–as far as we can tell, that’s just an Indian brand of PVA glue, so Elmer’s or any other white glue should do just as well.

A tachometer used to be an accessory added to the dash of only the sportiest of cars, but now they’re pretty much standard equipment on everything from sleek coupes to the family truckster. If your daily driver was born without a tach, fear not – a simple Arduino tachometer is well within your reach.

The tach-less vehicle in question is [deepsyx]’s Opel Astra, which from the video below seems to have the pep and manual transmission that would make a tach especially useful. Eschewing the traditional analog meter display or even a digital readout, [deepsyx] opted to indicate shift points with four LEDs mounted to a scrap of old credit card. The first LED lights at 4000 RPM, with subsequent LEDs coming on at each 500 RPM increase beyond that. At 5800 RPM, all the LEDs blink as a redline warning. [Deepsyx] even provides a serial output of the smoothed RPM value, so logging of RPM data is a possible future enhancement.

The project is sensing engine speed using the coil trigger signal – a signal sent from the Engine Control Unit (ECU) which tells one of the ignition coilpacks to fire. The high voltage signal from the coilpack passes on to the spark plug, which ignites the air-fuel mixture in that cylinder. This is a good way to determine engine RPM without mechanical modifications to the car. Just make sure you modify the code for the correct number of cylinders in your vehicle.

Simple, cheap, effective – even if it is more of a shift point indicator than true tachometer, it gets the job done. But if you’re looking for a more traditional display and have a more recent vintage car, this sweeping LED tachometer might suit you more.

Our wonderfully creative community has a penchant for clocks. We have seen so many timepieces over the years that one might suppose that there would be nothing new, no instrument of horology that would not elicit a yawn as we are presented with something we’ve seen many times before.

Every once in a while though along comes a project that is different. A clock that takes the basic idea of a timepiece and manages to present something new, proving that this particular well of projects has not yet quite run dry.

Such a project is the circular word clock made by [Roald Hendriks]. Take a conventional circular wall clock and remove the hands and mechanism, then place LEDs behind the numbers. Add the words for “Quarter”, “Half”, etc. in an inner ring, and place LEDs behind them. Hook all these LEDs up to a microcontroller with a real-time clock, and away you go with a refreshingly novel timepiece.

[Roald]’s clock has the wording in Dutch, and the brain behind it is an Arduino Uno with the relevant driver ICs. He’s provided a video which we’ve put below the break, showing the clock in operation with its various demo modes.

We’ve noticed a lot of musical groups are named after insects. Probably has something to do with the Beatles. (If you study that for a while you’ll spot the homophonic pun, and yes we know that the Crickets inspired the name.) There’s also Iron Butterfly, Adam Ant, and quite a few more. A recent art project by a Mexican team — Micro-ritmos — might inspire some musical groups to be named after bacteria.

The group used geobacter — a kind of bacteria found in soil — a Raspberry Pi, an Arduino, and a camera to build an interesting device. As it looks at the bacteria and uses SuperCollider to create music and lighting from the patterns. You can see a video of Micro-ritmos, below.

At its heart is an Arduino Uno and an Adafruit Motor Shield v2. The green laser is turned on and off by the Arduino through a transistor. But the part that makes this really a fun machine to watch at work are the two stepper motors and two mirrors that reflect the laser in the X and Y directions. The mirrors are rectangles cut from a hard disk platter, which if you’ve ever seen one, is very reflective. The servos tilt the mirrors at high speed, fast enough to make the resulting projection on the wall appear almost a solid shape, depending on the image.

He’s even written a Windows application (in C#) for remotely controlling the projector through bluetooth. From its interface you can select from around sixteen predefined shapes, including a what looks like a cat head, a heart, a person and various geometric objects and line configurations.

There is a sort of curving of the lines wherever the image consists of two lines forming an angle, as if the steppers are having trouble with momentum, but that’s probably to be expected given that they’re steppers controlling relatively large mirrors. Or maybe it’s due to twist in the connection between motor shaft and mirror? Check out the video after the break and let us know what you think.